IC including standard cells and SRAM cells

ABSTRACT

An IC is provided. The IC includes a plurality of a plurality of P-type fin field-effect transistors (FinFETs). The P-type FinFETs includes at least one first P-type FinFET and at least one second P-type FinFET. Source/drain regions of the first P-type FinFET have a first depth, and source/drain regions of the second P-type FinFET have a second depth that is different from the first depth. A first semiconductor fin of the first P-type FinFET includes a first portion and a second portion that are formed by different materials, and the second portion of the first semiconductor fin has a third depth that is greater than the first depth.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of application Ser. No. 16/513,857, filed on Jul. 17, 2019, now U.S. Pat. No. 10,825,835, the entirety of which is incorporated by reference herein.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component that can be created using a fabrication process) has decreased.

Static Random Access Memory (SRAM) is commonly used in integrated circuits. SRAM cells have the advantageous feature of being able to hold data without the need to refresh. With the increasingly demanding requirements on the speed of integrated circuits, the read speed and write speed of SRAM cells have also become more important. With increased down-scaling of the already very small SRAM cells, however, such requests are difficult to achieve.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various nodes are not drawn to scale. In fact, the dimensions of the various nodes may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a simplified diagram of an IC, in accordance with some embodiments of the disclosure.

FIG. 2A is a simplified diagram of a logic circuit, in accordance with some embodiments of the disclosure.

FIG. 2B is a simplified diagram of a logic circuit, in accordance with some embodiments of the disclosure.

FIG. 3A illustrates the logic symbol of the standard cell NAND.

FIG. 3B is a circuit diagram of the standard cell NAND in FIG. 3A.

FIG. 4A illustrates the logic symbol of the standard cell NOR.

FIG. 4B is a circuit diagram of the standard cell NOR in FIG. 4A.

FIG. 5A illustrates the logic symbol of the standard cell INV (i.e., inverter).

FIG. 5B is a circuit diagram of the standard cell INV in FIG. 5A.

FIG. 6 illustrates the layout of the semiconductor structure of a cell array, in accordance with some embodiments of the disclosure.

FIG. 7A illustrates a cross-sectional view of the semiconductor structure of the logic array along line A-AA in FIG. 6, in accordance with some embodiments of the disclosure.

FIG. 7B illustrates a cross-sectional view of the semiconductor structure of the logic array along line B-BB in FIG. 6, in accordance with some embodiments of the disclosure.

FIG. 8 illustrates the layout of the semiconductor structure of a cell array, in accordance with some embodiments of the disclosure.

FIG. 9 illustrates a cross-sectional view of the semiconductor structure of the logic array along line C-CC in FIG. 8, in accordance with some embodiments of the disclosure.

FIG. 10A is a simplified diagram of a memory, in accordance with some embodiments of the disclosure.

FIG. 10B is a simplified diagram of a memory, in accordance with some embodiments of the disclosure.

FIG. 11A illustrates a memory cell, in accordance with some embodiments of the disclosure.

FIG. 11B shows a simplified diagram of the memory cell of FIG. 11A, in accordance with some embodiments of the disclosure.

FIG. 12 illustrates the layout of the semiconductor structure of a memory array, in accordance with some embodiments of the disclosure.

FIG. 13 illustrates a cross-sectional view of the semiconductor structure of the memory array along line D-DD in FIG. 12, in accordance with some embodiments of the disclosure.

FIG. 14 illustrates the layout of the semiconductor structure of a memory array, in accordance with some embodiments of the disclosure.

FIG. 15 illustrates a cross-sectional view of the semiconductor structure of the memory array along line E-EE in FIG. 14, in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different nodes of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In some embodiments, the formation of a first node over or on a second node in the description that follows may include embodiments in which the first and the second nodes are formed in direct contact, and may also include embodiments in which additional nodes may be formed between the first and the second nodes, such that the first and the second nodes may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements. It should be understood that additional operations can be provided before, during, and/or after a disclosed method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Various semiconductor structures of integrated circuits (ICs) are provided in accordance with various exemplary embodiments. Some variations of some embodiments are discussed. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

FIG. 1 is a simplified diagram of an IC 100, in accordance with some embodiments of the disclosure. The IC 100 includes a logic circuit 110 and a memory 130. In some embodiments, the logic circuit 110 may be the controller for accessing the memory 130. In some embodiments, the logic circuit 110 is configured to perform a specific function or operation according to data stored in the memory 130. The logic circuit 110 includes multiple logic cells 10. In some embodiments, the logic cell 10 may be a standard cell (STD cell), e.g., inverter (INV), AND, OR, NAND, NOR, Flip-Flop, SCAN and so on. In some embodiments, the logic cells 10 corresponding to the same function or operation may have the same circuit configuration with different semiconductor structures for providing various threshold voltages (Vth or Vt). For example, the semiconductor structures of the transistors in the logic cells 10 a are different. In general, the threshold voltage of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain regions of the transistor.

In the IC 100, the memory 130 includes multiple memory cells 30 arranged in rows and columns of an array. In some embodiments, the memory cells 30 have the same circuit configuration and the same semiconductor structure. In some embodiments, the memory cell 30 may be a bit cell of SRAM.

FIG. 2A is a simplified diagram of a logic circuit 110A, in accordance with some embodiments of the disclosure. In the logic circuit 110A, multiple logic cells 10 a form a cell array 112 a, and the logic cells 10 a have the same cell width W. The logic array 112 a can be implemented in the logic circuit 110 of FIG. 1. In some embodiments, the logic array 112 a is capable of performing a specific function. In some embodiments, the logic array 112 a is capable of performing various functions. In some embodiments, each logic cell 10 a is the standard cell (e.g., inverter (INV), AND, OR, NAND, NOR, Flip-Flop, SCAN, etc.), a combination thereof or specific functional cells. Furthermore, each logic cell 10 a includes multiple transistors, i.e., PMOS and NMOS transistors.

In the logic array 112 a, five logic cells 10 a are positioned in the column COL1, and five logic cells 10 a are positioned in the column COL2. The NMOS transistors (not shown) of the logic cells 10 a in the column COL1 are formed over the P-type well region PW1, and the NMOS transistors (not shown) of the logic cells 10 a in the column COL2 are formed over the P-type well region PW2. Moreover, the PMOS transistors (not shown) of the logic cells 10 a in the columns COL1 and COL2 are formed over the N-type well region NW1.

In various embodiments, the columns in the logic array 112 a may include more logic cells 10 a or fewer logic cells 10 a than the layout shown in FIG. 2A. In various embodiments, the logic array 112 a may include more columns or fewer columns than the layout shown in FIG. 2A. Each logic cell 10 a provides a circuit or portion thereof, exemplary functionality provided by the logic cells 10 a includes, but are not limited to NAND circuit, a NOR circuit, AND circuit, XOR circuit, XNOR circuit, SACN, an inverter, a flip-flop, a latch, and/or other suitable logic or storage functions.

For the NMOS transistors in the logic cells 10 a in the logic array 112 a, the channel regions of the NMOS transistors are formed by the semiconductor fins 210 extending in the Y-direction. The semiconductor fins 210 are Si-base fins formed over the P-type well regions PW1 and PW2. For the logic cells 10 a in the same column COL1/COL2, the semiconductor fin 210 of each logic cell 10 a is separated from the semiconductor fins 210 of other logic cells 10 a by a dielectric-base gate 225 extending in the X-direction. In other words, the semiconductor fins 210 are discontinuous fin lines in the logic cells 10 a arranged in the same column COL1/COL2. The dielectric-base gate 225 is positioned between the cell boundary of two adjacent logic cells 10 a. In some embodiments, the width of the semiconductor fins 210 is from about 3 nm to about 12 nm.

For the PMOS transistors in the logic cells 10 a in the logic array 112 a, the channel regions of the PMOS transistors are formed by the semiconductor fins 215 extending in the Y-direction. The semiconductor fins 215 are SiGe fins formed over the N-type well region NW1. For the logic cells 10 a in the same column COL1/COL2, the semiconductor fin 215 of each logic cell 10 a is separated from the semiconductor fins 215 of other logic cells 10 a by a dielectric-base gate 225 extending in the X-direction. In other words, the semiconductor fins 215 are discontinuous fin lines in the logic cells 10 a in the same column COL1/COL2. The dielectric-base gates 225 are described below. In some embodiments, the width of the semiconductor fins 215 is from about 3 nm to about 12 nm. In some embodiments, the width of the semiconductor fins 210 is narrower than the width of the semiconductor fins 215.

The semiconductor fins 210/215 may be patterned by any suitable method. For example, the semiconductor fins 210/215 may be patterned using one or more photolithography processes, including double-patterning or multi-patterning processes. Generally, double-patterning or multi-patterning processes combine photolithography and self-aligned processes, allowing patterns to be created that have, for example, pitches smaller than what is otherwise obtainable using a single, direct photolithography process. For example, in one embodiment, a sacrificial layer is formed over a substrate and patterned using a photolithography process. Spacers are formed alongside the patterned sacrificial layer using a self-aligned process. The sacrificial layer is then removed, and the remaining spacers may then be used to pattern the semiconductor fins 210/215.

FIG. 2B is a simplified diagram of a logic circuit 110B, in accordance with some embodiments of the disclosure. In the logic circuit 110B, multiple logic cells 10 b form a cell array 112 b, and the logic cells 10 b have the same cell width W. The logic array 112 b can be implemented in the logic circuit 110 of FIG. 1. In some embodiments, the logic array 112 b is capable of performing a specific function. In some embodiments, the logic array 112 b is capable of performing various functions. In some embodiments, the logic cell 10 b is the standard cell (e.g., inverter (INV), AND, OR, NAND, NOR, Flip-Flop, SCAN, etc.), a combination thereof or specific functional cells. Furthermore, each of the logic cells 10 b includes multiple transistors, i.e., PMOS and NMOS transistors.

The configuration of logic cells 10 b in the logic array 112 b of the logic circuit 110B is similar to the configuration of logic cells 10 a in the logic array 112 a of the logic circuit 110A of FIG. 2A. The difference between the logic array 112 b and the logic array 112 a is that the semiconductor fins 210 and 215 are continuous fin lines in the logic cells 10 b in the same column COL1/COL2. In other words, the semiconductor fins 210 and 215 do not broken by the dielectric-base gates 225, and each semiconductor fin 210/215 is shared by the transistors over the same well region. For example, the semiconductor fin 210 over the P-type well region PW1 is shared by the NMOS transistors of the logic cells 10 b in the column COL1, and the semiconductor fin 215 over the N-type well region NW1 is shared by the PMOS transistors of the logic cells 10 b in the column COL1. Furthermore, the isolation NMOS transistors ISN and the isolation PMOS transistors ISP are located between the cell boundary of two adjacent logic cells 10 b for device isolation purposes. The isolation NMOS transistors ISN and the isolation PMOS transistors ISP are described below.

In some embodiments, the logic array 112 a of FIG. 2A and the logic array 112 b of FIG. 2B can be simultaneously implemented in the logic circuit 110 of FIG. 1.

FIG. 3A illustrates the logic symbol of the standard cell NAND. FIG. 3B is a circuit diagram of the standard cell NAND in FIG. 3A. The standard cell NAND is a logic gate configured to provide an output signal OUT1 according two input signals IN1 and IN2. The standard cell NAND includes two PMOS transistors P1 and P2 and two NMOS transistors N1 and N2. In some embodiments, the two PMOS transistors P1 and P2 and two NMOS transistors N1 and N2 may be the FinFETs with single fin or multiple-fin.

In the standard cell NAND, the PMOS transistors P1 and P2 are coupled in parallel between a node 31 and a power supply VDD. The NMOS transistor N1 is coupled between the node 31 and the NMOS transistor N2, and the NMOS transistor N2 is coupled between the NMOS transistor N1 and a ground VSS. The input signal IN1 is input to the gates of the PMOS transistor P1 and the NMOS transistor N1, and the input signal IN2 is input to the gates of the PMOS transistor P2 and the NMOS transistor N2. Furthermore, the output signal OUT1 is provided at the node 31.

FIG. 4A illustrates the logic symbol of the standard cell NOR. FIG. 4B is a circuit diagram of the standard cell NOR in FIG. 4A. The standard cell NOR is a logic gate configured to provide an output signal OUT2 according two input signals IN3 and IN4. The standard cell NOR includes two PMOS transistors P3 and P4 and two NMOS transistors N3 and N4. In some embodiments, the two PMOS transistors P3 and P4 and two NMOS transistors N3 and N4 may be the FinFETs with single fin or multiple-fin.

In the standard cell NOR, the PMOS transistor P3 is coupled between a power supply VDD and the PMOS transistor P4, and the PMOS transistor P4 is coupled between the PMOS transistor P3 and a node 32. The NMOS transistors N3 and N4 are coupled in parallel between the node 32 and a ground VSS. The input signal IN3 is input to the gates of the PMOS transistor P3 and the NMOS transistor N3, and the input signal IN4 is input to the gates of the PMOS transistor P4 and the NMOS transistor N4. Furthermore, the output signal OUT2 is provided at the node 32.

FIG. 5A illustrates the logic symbol of the standard cell INV (i.e., inverter). FIG. 5B is a circuit diagram of the standard cell INV in FIG. 5A. The standard cell INV is a logic gate configured to inverting an input signal IN to provide an output signal OUT. The standard cell INV includes a PMOS transistor P5 and an NMOS transistor N5. In some embodiments, the PMOS transistor P5 and the NMOS transistors N5 may be the FinFETs with single fin or multiple-fin.

In the standard cell INV, the PMOS transistor P5 is coupled between the NMOS transistor N5 and a power supply VDD. The NMOS transistor N5 is coupled between the PMOS transistor P5 and a ground VSS. The input signal IN is input to the gates of the PMOS transistor P5 and the NMOS transistor N5. Furthermore, the output signal OUT is provided at the drains of the NMOS transistor N5 and the PMOS transistor P5.

FIG. 6 illustrates the layout of the semiconductor structure of a cell array 112 a_1, in accordance with some embodiments of the disclosure. The logic array 112 a_1 includes the logic cells 10 a_1, 10 a_2 and 10 a_3 arranged in the same column. The logic array 112 a_1 can be implemented in the logic circuit 110 of FIG. 1. In some embodiments, the standard cell INV of FIGS. 5A and 5B is implemented in the logic cell 10 a_1, the standard cell NAND of FIGS. 3A and 3B is implemented in the logic cell 10 a_2, and the standard cell NOR of FIGS. 4A and 4B is implemented in the logic cell 10 a_3. In such embodiments, the transistors of the logic cells 10 a_1 through 10 a_3 are dual-fin FETs. Furthermore, the outer boundary of each of the logic cells 10 a_1 through 10 a_3 is illustrated using dashed lines.

In various embodiments, the columns in the logic array 112 a_1 may include more logic cells 10 a or fewer logic cells 10 a than the layout shown in FIG. 6. In various embodiments, the logic array 112 a_1 may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 6. Each logic cell 10 a provides a circuit or portion thereof, exemplary functionality provided by the logic cells 10 aincludes, but are not limited to NAND circuit, a NOR circuit, AND circuit, XOR circuit, XNOR circuit, SACN, an inverter, a flip-flop, a latch, and/or other suitable logic or storage functions.

In the logic cell 10 a_1, the semiconductor fins 215 a and 215 b extending in the Y-direction are formed over the N-type well region NW, and the semiconductor fins 210 a and 210 b extending in the Y-direction are formed over the P-type well region PW. As described above, the semiconductor fins 210 a and 210 b are Si-base fins, and the semiconductor fins 215 a and 215 b are SiGe fins. A gate electrode 220 a extending in the X-direction forms the PMOS transistor P5 with an underlying active region formed by the semiconductor fins 215 a and 215 b over the N-type well region NW. Furthermore, the gate electrode 220 a forms the NMOS transistor N5 with an underlying active region formed by the semiconductor fins 210 a and 210 a over the P-type well region PW. In other words, the gate electrode 220 a is shared by the NMOS transistor N5 and the PMOS transistor P5. In some embodiments, the gate electrode 220 a is coupled to a conductive line (not shown) extending in the Y-direction through a gate contact 255 a, and the conductive line is configured to connect the gate electrode 220 a to an overlying level for receiving the input signal IN.

In the logic cell 10 a_1, the source/drain region 230 a of the PMOS transistor P5 is coupled to an overlying level through the contact 245 a for coupling the power supply VDD. Furthermore, the source/drain region 230 c of the PMOS transistor P5 is coupled to an overlying level through the contact 245 c. Similarly, the source/drain region 230 b of the NMOS transistor N5 is coupled to an overlying level through the contact 245 b for coupling the ground VSS. Moreover, the source/drain region 230 d of the NMOS transistor N5 is coupled to an overlying level through the contact 245 d.

In the logic cell 10 a_1, the dielectric-base gates 225 a and 225 b extending in the X-direction are dummy gates. The gate electrode 220 a is arranged between the dielectric-base dummy gates 225 a and 225 b, and the NMOS transistor N5 and the PMOS transistor P5 are surrounded by the dielectric-base dummy gates 225 a and 225 b. In other words, the dielectric-base dummy gates 225 a and 225 b are arranged in the boundary of the logic cell 10 a_1.

In the logic cell 10 a_2, the semiconductor fins 215 c and 215 d extending in the Y-direction are formed over the N-type well region NW, and the semiconductor fins 210 c and 210 d extending in the Y-direction are formed over the P-type well region PW. As described above, the semiconductor fins 210 c and 210 d are Si-base fins, and the semiconductor fins 215 c and 215 d are SiGe fins. A gate electrode 220 b extending in the X-direction forms the PMOS transistor P2 with an underlying active region formed by the semiconductor fins 215 c and 215 d over the N-type well region NW. Furthermore, the gate electrode 220 b forms the NMOS transistor N2 with an underlying active region formed by the semiconductor fins 210 c and 210 d over the P-type well region PW. In other words, the gate electrode 220 b is shared by the NMOS transistor N2 and the PMOS transistor P2. In some embodiments, the gate electrode 220 b is coupled to a conductive line (not shown) extending in the Y-direction through a gate contact (not shown), and the conductive line is configured to connect the gate electrode 220 b to an overlying level for receiving the input signal IN2.

In the logic cell 10 a_2, a gate electrode 220 c extending in the X-direction forms the PMOS transistor P1 with an underlying active region formed by the semiconductor fins 215 c and 215 d over the N-type well region NW. Furthermore, the gate electrode 220 b forms the NMOS transistor N1 with an underlying active region formed by the semiconductor fins 210 c and 210 d over the P-type well region PW. In other words, the gate electrode 220 c is shared by the NMOS transistor N1 and the PMOS transistor P1. In some embodiments, the gate electrode 220 c is coupled to a conductive line (not shown) extending in the Y-direction through a gate contact (not shown), and the conductive line is configured to connect the gate electrode 220 c to an overlying level for receiving the input signal IN1.

In the logic cell 10 a_2, the source/drain region 230 e of the PMOS transistor P2 is coupled to an overlying level through the contact 245 e for coupling the power supply VDD. Similarly, the source/drain region 230 i of the PMOS transistor P1 is coupled to an overlying level through the contact 245 i for coupling the power supply VDD. Furthermore, the source/drain region 230 f of the NMOS transistor N2 is coupled to an overlying level through the contact 245 f for coupling the ground VSS. Moreover, the source/drain region 230 j of the NMOS transistor N1 is coupled to an overlying level through the contact 245 j.

The source/drain region 230 g is a common source/drain region for the PMOS transistors P1 and P2, and the source/drain region 230 g is coupled to an overlying level through the contact 245 g. Moreover, the source/drain region 230 h is a common source/drain region for the NMOS transistors N1 and N2. And the source/drain region 230 h is coupled to an overlying level through the contact 245 h.

In the logic cell 10 a_2, the dielectric-base gates 225 b and 225 c extending in the X-direction are dummy gates. The gate electrodes 220 b and 220 c are arranged between the dielectric-base dummy gates 225 b and 225 c, and the NMOS transistors N1 and N2 and the PMOS transistors P1 and P2 are surrounded by the dielectric-base dummy gates 225 b and 225 c. In other words, the dielectric-base dummy gates 225 b and 225 c are arranged in the boundary of the logic cell 10 a_2. Furthermore, the semiconductor fins 215 a and 215 b in the logic cell 10 a_1 are separated from the semiconductor fins 215 c and 215 d in the logic cell 10 a_2 by the dielectric-base dummy gate 225 b. Similarly, the semiconductor fins 210 a and 210 b in the logic cell 10 a_1 are also separated from the semiconductor fins 210 c and 210 d in the logic cell 10 a_2 by the dielectric-base dummy gate 225 b.

In the logic cell 10 a_3, the semiconductor fins 215 e and 215 f extending in the Y-direction are formed over the N-type well region NW, and the semiconductor fins 210 e and 210 f extending in the Y-direction are formed over the P-type well region PW. As described above, the semiconductor fins 210 e and 210 f are Si-base fins, and the semiconductor fins 215 e and 215 f are SiGe fins. A gate electrode 220 d extending in the X-direction forms the PMOS transistor P3 with an underlying active region formed by the semiconductor fins 215 e and 215 f over the N-type well region NW. Furthermore, the gate electrode 220 d forms the NMOS transistor N3 with an underlying active region formed by the semiconductor fins 210 e and 210 f over the P-type well region PW. In other words, the gate electrode 220 d is shared by the NMOS transistor N3 and the PMOS transistor P3. In some embodiments, the gate electrode 220 d is coupled to a conductive line (not shown) extending in the Y-direction through a gate contact (not shown), and the conductive line is configured to connect the gate electrode 220 d to an overlying level for receiving the input signal IN3.

In the logic cell 10 a_3, a gate electrode 220 e extending in the X-direction forms the PMOS transistor P4 with an underlying active region formed by the semiconductor fins 215 e and 215 f over the N-type well region NW. Furthermore, the gate electrode 220 e forms the NMOS transistor N4 with an underlying active region formed by the semiconductor fins 210 e and 210 f in the P-type well region PW. In other words, the gate electrode 220 e is shared by the NMOS transistor N4 and the PMOS transistor P4. In some embodiments, the gate electrode 220 e is coupled to a conductive line (not shown) extending in the Y-direction through a gate contact (not shown), and the conductive line is configured to connect the gate electrode 220 e to an overlying level for receiving the input signal IN4.

In the logic cell 10 a_3, the source/drain region 230 k of the PMOS transistor P3 is coupled to an overlying level through the contact 245 k for coupling the power supply VDD. Furthermore, the source/drain region 230 l of the NMOS transistor N3 is coupled to an overlying level through the contact 245 l for coupling the ground VSS. Similarly, the source/drain region 230 p of the NMOS transistor N4 is coupled to an overlying level through the contact 245 p for coupling the ground VSS. Moreover, the source/drain region 230 o of the PMOS transistor P4 is coupled to an overlying level through the contact 245 o.

The source/drain region 230 m is a common source/drain region for the PMOS transistors P3 and P4, and the source/drain region 230 m is coupled to an overlying level through the contact 245 m. Moreover, the source/drain region 230 n is a common source/drain region for the NMOS transistors N3 and N4. And the source/drain region 230 n is coupled to an overlying level through the contact 245 n.

In the logic cell 10 a_3, the dielectric-base gates 225 c and 225 d extending in the X-direction are dummy gates. The gate electrodes 220 d and 220 e are arranged between the dielectric-base dummy gates 225 c and 225 d, and the NMOS transistors N3 and N4 and the PMOS transistors P3 and P4 are surrounded by the dielectric-base dummy gates 225 c and 225 d. In other words, the dielectric-base dummy gates 225 c and 225 d are arranged in the boundary of the logic cell 10 a_3. Furthermore, the semiconductor fins 215 c and 215 d in the logic cell 10 a_2 are separated from the semiconductor fins 215 e and 215 f in the logic cell 10 a_3 by the dielectric-base dummy gate 225 c. Similarly, the semiconductor fins 210 c and 210 d in the logic cell 10 a_2 are also separated from the semiconductor fins 210 e and 210 f in the logic cell 10 a_3 by the dielectric-base dummy gate 225 d.

FIG. 7A illustrates a cross-sectional view of the semiconductor structure of the logic array 112 a_1 along line A-AA in FIG. 6, in accordance with some embodiments of the disclosure. The P-type well region PW and the N-type well region NW are formed over a substrate 310. In some embodiments, the substrate 310 is a Si substrate. In some embodiments, the material of the substrate 310 is selected from a group consisting of bulk-Si, SiP, SiGe, SiC, SiPC, Ge, SOI—Si, SOI—SiGe, III-VI material, and combinations thereof.

The semiconductor fins 215 a and 215 b are formed on the N-type well region NW. The semiconductor fins 215 a and 215 b are separated from each other by the shallow trench isolation (STI) 320. The semiconductor fin 215 a includes a first portion 215 a_1 and a second portion 215 a_2. Unlike the first portion 215 a_1, the second portion 215 a_2 further includes SiGe. Similarly, the semiconductor fin 215 b includes a first portion 215 b_1 and a second portion 215 b_2. Unlike the first portion 215 b_1, the second portion 215 b_2 further includes SiGe. In some embodiments, the Ge atomic concentration of the second portions 215 a_2 and 215 b_2 is from about 5% to about 45%. In some embodiments, the second portions 215 a_2 and 215 b_2 are formed by performing a dielectric deposition, patterning to expose the predetermined channel region and following a first SiGe concentration epi-growth on exposed channel region. For example, using mask to etch a predetermined area on the Si substrate 310 with a depth (e.g., 40 nm to 70 nm), and then the non-etch portion is blocked. Next, the SiGe epitaxy growth material is formed for the second portions 215 a_2 and 215 b_2, and then subsequent processes are performed to form the STI 320 and so on.

The semiconductor fins 210 a and 210 b are formed on the P-type well region PW. The semiconductor fins 210 a and 210 b are separated from each other by the STI 320. The semiconductor fins 210 a and 210 b are made of the same material. Unlike the semiconductor fins 215 a and 215 b, the semiconductor fins 210 a and 210 b do not include Ge.

The gate electrode 220 a is formed over the gate dielectric layer 335 and is positioned over a top surface of the semiconductor fins 210 a, 210 b, 215 a and 215 b. In some embodiments, the spacers 338 (shown in FIG. 7B) are formed on opposite sides of the gate electrode 335 and between the gate dielectric layer 335 and the Inter-Layer Dielectric (ILD) layer 330. Each of the semiconductor fins 215 a and 215 b overlapping the gate electrode 235, e.g., the second portions 215 a_2 and 215 b_2, may serve as a SiGe channel region of the PMOS transistor P5. Thus, the gate electrode 220 a and the gate dielectric layer 335 over the semiconductor fins 215 a and 215 b form a gate structure for the PMOS transistor P5. Furthermore, each of the semiconductor fins 210 a and 210 b overlapping the gate electrode 220 a may serve as a Si channel region of the NMOS transistor N5. Thus, the gate electrode 220 a and the gate dielectric layer 335 over the semiconductor fins 210 a and 210 b form a gate structure for the NMOS transistor N5. In some embodiments, the gate electrode 220 a is made of conductive material, such as aluminum (Al), copper (Cu), tungsten (W), titanium (Ti), tantalum (Ta), or other applicable materials.

The gate dielectric layer 335 may be a single layer or multiple layers. The gate dielectric layer 335 is made of silicon oxide (SiOx), silicon nitride (SixNy), silicon oxynitride (SiON), dielectric material(s) with high dielectric constant (high-k), or a combination thereof. In some embodiments, the gate dielectric layer 335 is deposited by a plasma enhanced chemical vapor deposition (PECVD) process or by a spin coating process. The high dielectric constant (high-k) material may be hafnium oxide (HfO₂), zirconium oxide (ZrO₂), lanthanum oxide (La₂O₃), yttrium oxide (Y₂O₃), aluminum oxide (Al₂O₃), titanium oxide (TiO₂) or another applicable material.

The ILD 330 is formed over the STI 320. The gate contact 255 a is formed over the metal electrode 220 a. In some embodiments, the ILD layer 330 may be formed of an oxide such as Phospho-Silicate Glass (PSG), Boro-Silicate Glass (BSG), Boron-Doped Phospho-Silicate Glass (BPSG), Tetra Ethyl Ortho Silicate (TEOS) oxide, or the like.

FIG. 7B illustrates a cross-sectional view of the semiconductor structure of the logic array 112 a_1 along line B-BB in FIG. 6, in accordance with some embodiments of the disclosure. The N-type well region NW is formed over the semiconductor substrate 310. The semiconductor fins 215 a, 215 c and 215 e are formed on the N-type well region NW. As described above, the semiconductor fin 215 a includes a first portion 215 a_1 and a second portion 215 a_2. Similarly, the semiconductor fin 215 c includes a first portion 215 c_1 and a second portion 215 c_2, and the semiconductor fin 215 e includes a first portion 215 e_1 and a second portion 215 e_2. The semiconductor fins 215 a, 215 c and 215 e are separated from each other by the dielectric-base dummy gates 225 a and 225 c. In some embodiments, the depth D3 of the second portions 215 a_2, 215 c_2, and 215 e_2 of the semiconductor fins 215 a, 215 c and 215 e is from about 30 nm to about 90 nm.

The source/drain regions 230 a and 230 c of the PMOS transistor P5 are formed by the P-type doping regions on the semiconductor fin 215 a. The contacts 245 a and 245 c are formed over the source/drain regions 230 a and 230 c, respectively. The source/drain regions 230 e, 230 g and 230 i of the PMOS transistors P2 and P1 are formed by the P-type doping regions on the semiconductor fin 215 c. The contacts 245 e, 245 g and 245 i are formed over the source/drain regions 230 e, 230 g and 230 i, respectively. The source/drain regions 230 k, 230 m and 230 o of the PMOS transistors P3 and P4 are formed by the P-type doping regions on the semiconductor fin 215 e. The contacts 245 k, 245 m and 245 o are formed over the source/drain regions 230 k, 230 m and 230 o, respectively.

In some embodiments, the source/drain silicide regions (not shown) are formed on the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o. In some embodiments, each of the contacts 245 a, 245 c, 245 e, 245 g, 245 i, 245 k, 245 m and 450 o includes a metal plug (not shown) and a high-K dielectric (not shown) formed on the sidewall of the metal plug. In other words, the metal plug is surrounded by the high-K dielectric. In order to simplify the description, the source/drain silicide regions, the metal plugs, and the high-K dielectric are omitted.

The gate electrode 220 a is formed over the gate dielectrics 335 and is positioned over a top surface of the second portion 215 a_2 of the semiconductor fin 215 a and between the source/drain regions 230 a and 230 c. The second portion 215 a_2 of the semiconductor fin 215 a overlapping the gate electrode 220 a, may serve as a SiGe channel region of the PMOS transistor P5. Furthermore, the spacers 338 are formed on opposite sides of the gate electrode 220 a. Thus, the gate electrode 220 a, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the second portion 215 a_2 of the semiconductor fin 215 a form a gate structure for the PMOS transistor P5.

The gate electrode 220 b is formed over the gate dielectrics 335 and is positioned over a top surface of the second portion 215 c_2 of the semiconductor fin 215 c and between the source/drain regions 230 e and 230 g. The second portion 215 c_2 of the semiconductor fin 215 c overlapping the gate electrode 220 b, may serve as a SiGe channel region of the PMOS transistor P2. Furthermore, the spacers 338 are formed on opposite sides of the gate electrode 220 b. Thus, the gate electrode 220 b, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the second portion 215 c_2 of the semiconductor fin 215 c form a gate structure for the PMOS transistor P2.

The gate electrode 220 c is formed over the gate dielectrics 335 and is positioned over a top surface of the second portion 215 c_2 of the semiconductor fin 215 c and between the source/drain regions 230 g and 230 i. The second portion 215 c_2 of the semiconductor fin 215 c overlapping the gate electrode 220 c, may serve as a SiGe channel region of the PMOS transistor P1. The gate electrode 220 c, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the second portion 215 c_2 of the semiconductor fin 215 c form a gate structure for the PMOS transistor P1.

The gate electrode 220 d is formed over the gate dielectrics 335 and is positioned over a top surface of the second portion 215 e_2 of the semiconductor fin 215 e and between the source/drain regions 230 k and 230 m. The second portion 215 e_2 of the semiconductor fin 215 e overlapping the gate electrode 220 d, may serve as a SiGe channel region of the PMOS transistor P3. The gate electrode 220 d, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the second portion 215 e_2 of the semiconductor fin 215 e form a gate structure for the PMOS transistor P3.

The gate electrode 220 e is formed over the gate dielectrics 335 and is positioned over a top surface of the second portion 215 e_2 of the semiconductor fin 215 e and between the source/drain regions 230 m and 230 o. The second portion 215 e_2 of the semiconductor fin 215 e overlapping the gate electrode 220 e, may serve as a SiGe channel region of the PMOS transistor P4. The gate electrode 220 e, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the second portion 215 e_2 of the semiconductor fin 215 e form a gate structure for the PMOS transistor P4.

In some embodiments, the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o include SiGe with Boron epitaxy growth material (i.e., boron-doped SiGe). In some embodiments, the Ge atomic concentration of the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o is from about 30% to about 75%. Furthermore, the source/drain regions of the NMOS transistors N1 through N3 are formed by epitaxy material, and the epitaxy material is selected from a group consisting of SiP, SiC, SiPC, SiAs, Si, and combinations thereof. In some embodiments, the depth D1 of the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o is from about 40 nm to 70 nm. Furthermore, the width W1 of the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o is greater than the SiGe channel regions of the PMOS transistors P1 through P5. For example, the semiconductor fin 215 c overlapping the gate electrode 220 c, may serve as the SiGe channel region of the PMOS transistor P1, and the SiGe channel region of the PMOS transistor P1 is narrower than the width W1 of the source/drain region 230 g.

In some embodiments, the Ge atomic concentration in the SiGe channel regions of the PMOS transistors P1 through P5 is from 5% to 45%. In some embodiments, the Ge atomic concentration of the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 o is greater than the Ge atomic concentration in the SiGe channel regions of the PMOS transistors P1 through P5.

Similar to the gate electrodes 220 a, 220 c and 220 e, the spacers 338 are formed on opposite sides of each of the dielectric-base dummy gates 225 a through 225 d. Furthermore, the dielectric-base dummy gates 225 a through 225 d are located upon the edge of the semiconductor fins 215 a, 215 c and 215 e. The semiconductor fins 215 a and 215 c are separated by the dielectric-base dummy gate 225 b, and the semiconductor fins 215 c and 215 e are separated by the dielectric-base dummy gate 225 c. Furthermore, the dielectric-base dummy gates 225 a through 225 d are deeper than the source/drain regions 230 a, 230 c, 230 e, 230 g, 230 i, 230 k, 230 m and 230 and the second portions 215 a_2, 215 c_2, and 215 e_2 of the semiconductor fins 215 a, 215 c and 215 e. In some embodiments, the width of the dielectric-base dummy gates 225 a through 225 d is substantially the same as that of the gate electrodes 220 a through 220 e.

The dielectric-base dummy gates 225 a through 225 d are formed by a single dielectric layer or multiple dielectric layers with material selected from a group consisting of SiO₂, SiOC, SiON, SiOCN, Carbon oxide, Nitrogen oxide, Carbon and Nitrogen oxide, metal oxide dielectric, Hf oxide (HfO₂), Ta oxide (Ta₂O₅), Ti oxide (TiO₂), Zr oxide (ZrO₂), Al oxide (Al₂O₃), Y oxide (Y₂O₃), multiple metal oxide, or a combination thereof.

In some embodiments, each gate structure of the gate electrodes 220 a through 220 e includes multiple material structure selected from a group consisting of poly gate/SiON structure, metals/high-K dielectric structure, Al/refractory metals/high-K dielectric structure, silicide/high-K dielectric structure, or a combination thereof.

FIG. 8 illustrates the layout of the semiconductor structure of a cell array 112 b_1, in accordance with some embodiments of the disclosure. The logic array 112 b_1 includes the logic cells 10 b_1, 10 b_2 and 10 b_3 arranged in the same column. In some embodiments, the standard cell INV of FIGS. 5A and 5B is implemented in the logic cell 10 b_1, the standard cell NAND of FIGS. 3A and 3B is implemented in the logic cell 10 b_2, and the standard cell NOR of FIGS. 4A and 4B is implemented in the logic cell 10 b_3. The transistors of the logic cells 10 b_1 through 10 b_3 are dual-fin FETs. Furthermore, the outer boundary of each of the logic cells 10 b_1 through 10 b_3 is illustrated using dashed lines.

In various embodiments, the columns in the logic array 112 b_1 may include more logic cells 10 b or fewer logic cells 10 b than the layout shown in FIG. 8. In various embodiments, the logic array 112 b_1 may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 8. Each logic cell 10 b provides a circuit or portion thereof, exemplary functionality provided by the logic cells 10 b includes, but are not limited to NAND circuit, a NOR circuit, AND circuit, XOR circuit, XNOR circuit, SACN, an inverter, a flip-flop, a latch, and/or other suitable logic or storage functions.

The configuration of logic cells 10 b_1 through 10 b_3 in the logic array 112 b_1 of FIG. 8 is similar to the configuration of logic cells 10 a_1 through 10 a_3 in the logic array 112 a_1 of FIG. 6. The difference between the logic array 112 b_1 and the logic array 112 a_1 is that the semiconductor fins 210 g and 210 h and the semiconductor fins 215 g and 215 h are continuous fin lines in the logic cells 10 b_1 through 10 b_3. In other words, the semiconductor fins 210 g and 210 h are shared by the NMOS transistors N1 through N5, and the semiconductor fins 215 g and 215 h are shared by the PMOS transistors P1 through P5. Therefore, the semiconductor fins 210 g and 210 h and the semiconductor fins 215 g and 215 h do not broken by any dielectric-base gates 225.

Multiple dummy gate electrodes are arranged on the cell boundary of two adjacent logic cells, so as to form the isolation transistors (e.g., the isolation NMOS transistors ISN and the isolation PMOS transistors ISP in FIG. 2B).

In the logic array 112 b_1, the dummy gate electrode 220 g_1 is positioned between the logic cells 10 b_1 and 10 b_2 and over the N-type well region NW, and the semiconductor fins 215 g and 215 h overlapping the dummy gate electrode 220 g_1, may serve as the SiGe channel regions of the isolation PMOS transistor ISP2. Furthermore, the dummy gate electrode 220 g_2 is positioned between the logic cells 10 b_1 and 10 b_2 and over the P-type well region PW, and the semiconductor fins 210 g and 210 h overlapping the dummy gate electrode 220 g_2, may serve as the Si channel regions of the isolation NMOS transistors ISN2. Similarly, the dummy gate electrode 220 h_1 is positioned between the logic cells 10 b_2 and 10 b_3 and over the N-type well region NW, and the semiconductor fins 215 g and 215 h overlapping the dummy gate electrode 220 h_1, may serve as the SiGe channel regions of the isolation PMOS transistors ISP3. Furthermore, the dummy gate electrode 220 h_2 is positioned between the logic cells 10 b_2 and 10 b_3 and over the P-type well region PW, and the semiconductor fins 210 g and 210 h overlapping the dummy gate electrode 220 h_2, may serve as the Si channel regions of the isolation NMOS transistors ISN3.

In some embodiments, other cell logics (not shown) are adjacent to the logic cell 10 b_1/10 b_3 in the same column. Thus, the semiconductor fins 215 g and 215 h overlapping the dummy gate electrode 220 f_1, may serve as the SiGe channel regions of the isolation PMOS transistors ISP1, and the semiconductor fins 210 g and 210 h overlapping the dummy gate electrode 220 f_2, may serve as the Si channel regions of the isolation NMOS transistors ISN1. Moreover, the semiconductor fins 215 g and 215 h overlapping the dummy gate electrode 220 i_1, may serve as the SiGe channel regions of the isolation PMOS transistors ISP4, and the semiconductor fins 210 g and 210 h overlapping the dummy gate electrode 220 i_2, may serve as the Si channel regions of the isolation NMOS transistors ISN4.

In the logic array 112 b_1, the dummy gate electrodes 220 f_1, 220 g_1, 220 h_1, and 220 i_1 are coupled to an overlying level (not shown) for coupling the power supply VDD. Moreover, the dummy gate electrodes 220 f_2, 220 g_2, 220 h_2, and 220 i_2 are coupled to an overlying level (not shown) for coupling the ground VSS.

FIG. 9 illustrates a cross-sectional view of the semiconductor structure of the logic array 112 b_1 along line C-CC in FIG. 8, in accordance with some embodiments of the disclosure. The N-type well region NW is formed over the semiconductor substrate 310. The semiconductor fin 215 g is formed on the N-type well region NW. The semiconductor fin 215 g includes a first portion 215 g_1 and a second portion 215 g_2. As described above, the semiconductor fin 215 g is a continuous fin line. As described above, the depth D3 of the second portion 215 g_2 of the semiconductor fin 215 g is from about 30 nm to about 90 nm.

The difference between the logic array 112 b_1 of FIG. 9 and the logic array 112 a_1 of FIG. 7B is that the dielectric-base dummy gates 225 a through 225 d in FIG. 7B are replaced with the dummy gate electrodes 220 f_1, 220 g_1, 220 h_1, and 220 i_1, respectively. Each gate structure of the dummy gate electrodes 220 f_1, 220 g_1, 220 h_1, and 220 i_1 and the two adjacent source/drain regions may form an isolation PMOS transistor ISP. For example, the source/drain regions 230 c and 230 e and the gate structure of the dummy gate electrode 220 g_1 form the isolation PMOS transistor ISP2 between the PMOS transistors P5 and P2, and the source/drain regions 230 i and 230 k and the gate structure of the dummy gate electrode 220 h_1 form the isolation PMOS transistor ISP3 between the PMOS transistors P1 and P3.

FIG. 10A is a simplified diagram of a memory 130A, in accordance with some embodiments of the disclosure. In the memory 130A, multiple memory cells 30 a form a memory array 132 a, and the memory cells 30 a have the same cell width W1 and the same cell height H1. In some embodiments, the memory cell 30 a may be a bit cell of SRAM. Furthermore, each memory cell 30 a includes multiple transistors, i.e., PMOS and NMOS transistors. The memory cell 30 a are described below.

In the memory array 132 a, four memory cells 30 a are positioned in the column COL3, and four memory cells 30 a are positioned in the column COL4. The NMOS transistors of the memory cells 30 a in the column COL3 are formed over the P-type well regions PW1 and PW2, and the NMOS transistors of the memory cells 30 a in the column COL4 are formed over the P-type well regions PW2 and PW3. Moreover, the PMOS transistors of the memory cells 30 a in the column COL3 are formed over the N-type well region NW1, and the PMOS transistors of the memory cells 30 a in the column COL4 are formed over the N-type well region NW2.

In various embodiments, the columns in the memory array 132 a may include more memory cells 30 a or fewer memory cells 30 a than the layout shown in FIG. 10A. In various embodiments, the memory array 132 a may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 10A.

For the PMOS and NMOS transistors in the memory cells 30 a, the channel regions of the transistors are formed by the semiconductor fins 210 extending in the Y-direction. The semiconductor fins 210 are Si-base fins, and the semiconductor fins 210 are continuous fin lines. In some embodiments, the width of the semiconductor fins 210 is from about 3 nm to about 12 nm.

FIG. 10B is a simplified diagram of a memory 130B, in accordance with some embodiments of the disclosure. In the memory 130B, multiple memory cells 30 b form a memory array 132 b, and the memory cells 30 b have the same cell width W1 and the same cell height H. In some embodiments, the memory cell 30 b may be a bit cell of SRAM. Furthermore, each memory cell 30 b includes multiple transistors, i.e., PMOS and NMOS transistors. The memory cell 30 b is described below.

The configuration of memory cells 30 b in the memory array 132 b of the memory 130B is similar to the configuration of memory cells 30 a in the memory array 132 a of the memory 130A of FIG. 10A. The difference between the memory array 132 b and the memory array 132 a is that the semiconductor fins 210 over the N-type well regions NW1 and NW2 are discontinuous fin lines in the memory array 132 b. Furthermore, on the N-type well regions NW1 and NW2, each semiconductor fin 210 is shared by the PMOS transistors of two adjacent memory cells 30 b in the same column.

In some embodiments, the memory array 132 a of FIG. 10A and/or the memory array 132 b of FIG. 10B can be implemented in the memory 130 of FIG. 1.

In various embodiments, the columns in the memory array 132 b may include more memory cells 30 b or fewer memory cells 30 b than the layout shown in FIG. 10B. In various embodiments, the memory array 132 b may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 10B.

FIG. 11A illustrates a memory cell 30 (or 30 a/30 b), in accordance with some embodiments of the disclosure. In this embodiment, the memory cell 30 is a single-port SRAM bit cell. The memory cell 30 includes a pair of cross-coupled inverters Inverter-1 and Inverter-2, and two pass-gate transistors PG-1 and PG-2. The inverters Inverter-1 and Inverter-2 are cross-coupled between the nodes n2 and n1, and form a latch. The pass-gate transistor PG-1 is coupled between a bit line BL and the node n2, and the pass-gate transistor PG-2 is coupled between a complementary bit line BLB and the node n1, wherein the complementary bit line BLB is complementary to the bit line BL. The gates of the pass-gate transistors PG-1 and PG-2 are coupled to the same word-line WL. Furthermore, the pass-gate transistors PG-1 and PG-2 are NMOS transistors.

FIG. 11B shows a simplified diagram of the memory cell 30 of FIG. 11A, in accordance with some embodiments of the disclosure. The inverter Inverter-1 includes a pull-up transistor PU-1 and a pull-down transistor PD-1. The pull-up transistor PU-1 is a PMOS transistor, and the pull-down transistor PD-1 is an NMOS transistor. The drain of the pull-up transistor PU-1 and the drain of the pull-down transistor PD-1 are coupled to the node n2 connecting the pass-gate transistor PG-1. The gates of the pull-up transistor PU-1 and the pull-down transistor PD-1 are coupled to the node n1 connecting the pass-gate transistor PG-2. Furthermore, the source of the pull-up transistor PU-1 is coupled to the power supply VDD, and the source of the pull-down transistor PD-1 is coupled to a ground VSS.

Similarly, the inverter Inverter-2 includes a pull-up transistor PU-2 and a pull-down transistor PD-2. The pull-up transistor PU-2 is a PMOS transistor, and the pull-down transistor PD-2 is an NMOS transistor. The drains of the pull-up transistor PU-2 and the pull-down transistor PD-2 are coupled to the node n1 connecting the pass-gate transistor PG-2. The gates of the pull-up transistor PU-2 and the pull-down transistor PD-2 are coupled to the node n2 connecting the pass gate transistor PG-1. Furthermore, the source of the pull-up transistor PU-2 is coupled to the power supply VDD, and the source of the pull-down transistor PD-2 is coupled to the ground VSS.

In some embodiments, the pass-gate transistors PG-1 and PG-2, the pull-up transistors PU-1 and PU-2, and the pull-down transistors PD-1 and PD-2 of the memory cell 30 are FinFETs. In some embodiments, the pass-gate transistors PG-1 and PG-2 and the pull-down transistors PD-1 and PD-2 are the single-fin FETs, and the pull-up transistors PU-1 and PU-2 are the single-fin FETs or the dual-fin FETs.

FIG. 12 illustrates the layout of the semiconductor structure of a memory array 132 a_1, in accordance with some embodiments of the disclosure. The memory array 132 a_1 includes the memory cells 30 a_1 and 30 a_2 arranged in the same column, and the memory cells 30 a_1 and 30 a_2 are single-port SRAM bit cells of FIGS. 11A and 11B. The memory array 132 a_1 can be implemented in the memory 130 of FIG. 1. The outer boundary of each of the memory cells 30 a_1 and 30 a_2 is illustrated using dashed lines. Furthermore, the two memory cells 30 a_1 and 30 a_2 are arranged in mirror symmetry along the X-direction.

In various embodiments, the columns in the memory array 132 a_1 may include more memory cells 30 a or fewer memory cells 30 a than the layout shown in FIG. 12. In various embodiments, the memory array 132 a_1 may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 12.

An N-type well region NW1 is at the middle of memory cells 30 a_1 and 30 a_2, and two P-type well regions PW1 and PW2 are on opposite sides of N-type well region NW1. The semiconductor fin 210_1 extending in the Y-direction is a continuous Si-base fin line formed over the P-type well region PW1, and the semiconductor fin 210_4 extending in the Y-direction is a continuous Si-base fin line formed over the P-type well region PW2. Moreover, the semiconductor fins 210_3 and 210_4 extending in the Y-direction are the continuous Si-base fin lines formed over the N-type well region NW1.

The gate electrode 220_1 forms the pull-up transistor PU-1 with an underlying semiconductor fin 210_2 over the N-type well region NW1. The gate electrode 220_1 further forms the pull-down transistor PD-1 with the underlying semiconductor fin 210_1 in P-type well region PW1. In other words, the gate electrode 220_1 is shared by the pull-up transistor PU-1 and the pull-down transistor PD-1. The gate electrode 220_3 forms the pass-gate transistor PG-1 with the semiconductor fin 210_1. In other words, the semiconductor fin 210_1 is shared by the pass-gate transistor PG-1 and the pull-down transistor PD-1. Furthermore, the gate electrode 220_3 is coupled to the corresponding via 250 through the contact 260_3. The contact 260_3 is a butt contact, and includes a portion over, and electrically connected to, the gate electrode 220_3.

The gate electrode 220_4 forms the pull-up transistor PU-2 with an underlying semiconductor fin 210_3 over the N-type well region NW1. The gate electrode 220_4 further forms the pull-down transistor PD-2 with an underlying semiconductor fin 210_4 in the P-type well region PW2. In other words, the gate electrode 220_4 is shared by the pull-up transistor PU-2 and the pull-down transistor PD-2. The gate electrode 220_2 forms the pass-gate transistor PG-2 with the underlying semiconductor fin 210_4. In other words, the semiconductor fin 210_4 is shared by the pass-gate transistor PG-2 and the pull-down transistor PD-2. Furthermore, the gate electrode 220_2 is coupled to the corresponding via 250 through the contact 260_4. The contact 260_4 is a butt contact, and includes a portion over, and electrically connected to, the gate electrode 220_2.

The contacts 245_1 and 245_10 are used to connect to the source/drain regions 230_1 and 230_12 of the pull-down transistors PD-1 and PD-2 to the VSS lines (e.g., the ground VSS) through the corresponding vias 250. The contacts 245_1 and 245_10 have lengthwise directions parallel to the X direction, and may be formed to overlap the corners of the memory cells 30 a_1 and 30 a_2. The contacts 245_2 and 245_9 are used to connect to the source/drain regions 230_2 and 230_11 of pull-up transistors PU-1 and PU-2 to the VDD lines (e.g., the supply voltage VDD) through the corresponding vias 250. Additionally, the contact 245_8 is used to connect to the source/drain region 230_9 of pass-gate transistor PG-1 to a bit line BL through the corresponding via 250. The contact 245_3 is used to connect to the source/drain region 230_4 of the pass-gate transistor PG-2 to a complementary bit line BLB through the corresponding via 250.

The contact 245_6 is a longer contact, and is elongated and has a longitudinal direction in the X direction, which is parallel to the extending directions of the gate electrodes 220_1 through 220_4. The contact 260_2 is a butt contact, and includes a portion over, and electrically connected to, the gate electrode 220_1. In the manufacturing of the memory cell 30 a_1 on the semiconductor wafers, the contact 260_2 and the contact 245_6 may be formed as a single continuous butt contact. The source/drain region 230_7 of the pull-up transistor PU-2 is coupled to the source/drain region 230_8 of the pull-down transistor PD-2 and the pass-gate transistor PG-2 through the contact 245_6. Moreover, the contact 245_6 is coupled to the gate electrode 220_1 through the contact 260_2.

The contact 245_5 is a longer contact, and is elongated and has a longitudinal direction in the X direction. The contact 260_1 is a butt contact, and includes a portion over, and electrically connected to, the gate electrode 220_4. In the manufacturing of the memory cell 30 a_1 on the semiconductor wafers, the contact 260_1 and the contact 245_5 may be formed as a single continuous butt contact. The source/drain region 230_6 of the pull-up transistor PU-1 is coupled to the source/drain region 230_5 of the pull-down transistor PD-1 and the pass-gate transistor PG-1 through the contact 245_5. Moreover, the contact 245_5 is coupled to the gate electrode 220_4 through the contact 260_1.

In some embodiments, the gate structure of the gate electrode 220_4 and the source/drain regions 230_6 and 230_10 form the isolation PMOS transistor IS_1. The semiconductor fin 210_2 overlapping the gate electrode 220_4, may serve as the Si channel regions of the isolation PMOS transistor IS_1. Furthermore, the gate structure of the gate electrode 220_1 and the source/drain regions 230_3 and 230_7 form the isolation PMOS transistor IS_2. The semiconductor fin 210_3 overlapping the gate electrode 220_1, may serve as the Si channel regions of the isolation PMOS transistor IS_2.

FIG. 13 illustrates a cross-sectional view of the semiconductor structure of the memory array 132 a_1 along line D-DD in FIG. 12, in accordance with some embodiments of the disclosure. The N-type well region NW1 is formed over the semiconductor substrate 310. The semiconductor fin 210_2 is formed on the N-type well region NW1.

In the memory cell 30 a_1, the source/drain regions 230_2 and 230_6 of the pull-up transistor PU-1 are formed by the P-type doping regions on the semiconductor fin 210_2. The contacts 245_2 and 245_5 are formed over the source/drain regions 230_2 and 230_6, respectively. The source/drain regions 230_6 and 230_10 of the isolation PMOS transistor IS_1 are formed by the P-type doping regions on the semiconductor fin 210_2. Furthermore, no contact is formed over the source/drain region 230_10.

In the memory cell 30 a_2, the source/drain regions 230_14 and 230_13 of the pull-up transistor PU-1 are formed by the P-type doping regions on the semiconductor fin 210_2. The contacts 245_7 and 245_4 are formed over the source/drain regions 230_14 and 230_13, respectively. The source/drain regions 230_13 and 230_10 of the isolation PMOS transistor IS_1 are formed by the P-type doping regions on the semiconductor fin 210_2. As described above, no contact is formed over the source/drain region 230_10.

In some embodiments, the source/drain silicide regions (not shown) are formed on the source/drain regions 230_2, 230_6, 230_10, 230_13 and 230_14. In some embodiments, each of the contacts 245_2, 245_5, 245_4 and 245_7 includes a metal plug (not shown) and a high-K dielectric (not shown) formed on the sidewall of the metal plug. In other words, the metal plug is surrounded by the high-K dielectric. In order to simplify the description, the source/drain silicide regions, the metal plugs, and the high-K dielectric will be omitted.

The gate electrode 220_1 is formed over the gate dielectrics 335 and is positioned over a top surface of the semiconductor fin 210_2 and between the source/drain regions 230_2 and 230_6. The semiconductor fin 210_2 overlapping the gate electrode 220_1, may serve as a Si channel region of the pull-up transistor PU-1. Furthermore, the spacers 338 are formed on opposite sides of the gate electrode 220_1. Thus, the gate electrode 220_1, the corresponding gate dielectrics 335 and the corresponding spacers 338 over the semiconductor fin 210_2 form a gate structure for the pull-up transistor PU-1.

The gate electrode 220_4 is formed over the gate dielectrics 335 and is positioned over a top surface of the semiconductor fin 210_2 and between the source/drain regions 230_6 and 230_10. The semiconductor fin 210_2 overlapping the gate electrode 220_4, may serve as a Si channel region of the isolation PMOS transistor IS_1. Furthermore, the gate electrode 220_4 is coupled to the contact 245_5 through the contact 260_1. As described above, The contact 260_1 is a butt contact, and includes a portion over, and electrically connected to, the gate electrode 220_4.

In such embodiments, the configurations of the isolation PMOS transistor IS_1 and pull-up transistor PU-1 in the memory cell 30 a_2 may be similar to the isolation PMOS transistor IS_1 and pull-up transistor PU-1 in the memory cell 30 a_1, respectively, and are not repeated herein for simplicity.

In some embodiments, the source/drain regions 230_2, 230_6, 230_10, 230_13 and 230_14 include boron-doped SiGe. In some embodiments, the Ge atomic concentration of the source/drain regions 230_2, 230_6, 230_10, 230_13 and 230_14 is from about 30% to about 75%. Furthermore, the source/drain regions of the pass-gate transistors PG-1 and PG-2 and the pull-down transistors PD-1 and PD-2 are formed by epitaxy material, and the epitaxy material is selected from a group consisting of SiP, SiC, SiPC, SiAs, SiAsP, Si, and combinations thereof. In some embodiments, the depth D2 of the source/drain regions 230_2, 230_6, 230_10, 230_13 and 230_14 is from about 35 nm to 65 nm. Furthermore, the width W2 of the source/drain regions 230_2, 230_6, 230_10, 230_13 and 230_14 is greater than the Si channel regions of the pull-up transistors PU-1.

In an IC (e.g., the IC 100 of FIG. 1), the depth D2 (as shown in FIG. 13) of the source/drain regions of the PMOS transistors having the Si channel regions in a memory circuit (e.g., 130 of FIG. 1, 130A of FIG. 10A, and 130B of FIG. 10B) is less (or shallower) than the depth D1 (as shown in FIG. 7B and FIG. 9) of the source/drain regions of the PMOS transistors having the SiGe channel regions in a logic circuit (e.g., 110 of FIG. 1, 110A of FIG. 2A, and 110B of FIG. 2B), i.e., D2<D1. In some embodiments, the depth D1 is from about 40 nm to 70 nm, and the depth D2 is from about 35 nm to 65 nm. In some embodiments, the difference between the depth D1 and the depth D2 is greater than 3 nm. In some embodiments, the difference between the depth D1 and the depth D2 is from about 3 nm to 15 nm. In some embodiments, the difference between the depth D1 and the depth D2 is greater than 5%. In some embodiments, the difference between the depth D1 and the depth D2 is from about 5% to about 30%.

FIG. 14 illustrates the layout of the semiconductor structure of a memory array 132 b_1, in accordance with some embodiments of the disclosure. The memory array 132 b_1 includes the memory cells 30 b_1 and 30 b_2 arranged in the same column, and the memory cells 30 b_1 and 30 b_2 are single-port SRAM bit cells of FIGS. 11A and 11B. The memory array 132 b_1 can be implemented in the memory 130 of FIG. 1. The outer boundary of each of the memory cells 30 b_1 and 30 b_2 is illustrated using dashed lines. Furthermore, the two memory cells 30 b_1 and 30 b_2 are arranged in mirror symmetry along the X-direction.

In various embodiments, the columns in the memory array 132 b_1 may include more memory cells 30 b or fewer logic cells 30 b than the layout shown in FIG. 14. In various embodiments, the memory array 132 b_1 may include more rows or fewer rows and more columns or fewer columns than the layout shown in FIG. 14.

The configuration of memory cells 30 b_1 and 30 b_2 in the memory array 132 b_1 of FIG. 14 is similar to the configuration of memory cells 30 a_1 and 30 a_2 in the memory array 132 a_1 of FIG. 12. The difference between the memory array 132 b_1 and the memory array 132 a_1 is that the semiconductor fins 210_2 a, 210_2 b and 210_3 a are discontinuous fin lines over the N-type well region NW1. Thus, no isolation transistor is formed on the N-type well region NW1. For example, no source/drain regions 230_10 and 230_3 are formed in the memory array 132 b_1.

FIG. 15 illustrates a cross-sectional view of the semiconductor structure of the memory array 132 b_1 along line E-EE in FIG. 14, in accordance with some embodiments of the disclosure. The N-type well region NW1 is formed over the semiconductor substrate 310. The semiconductor fins 210_2 a and 210_2 b are formed on the N-type well region NW1. The difference between the memory array 132 b_1 of FIG. 15 and the memory array 132 a_1 of FIG. 13 is that the semiconductor fins 210_2 a and 210_2 b are separated from each other by the STI 320 in FIG. 15.

Embodiments of ICs including multiple logic cells and multiple SRAM cells are provided. The logic cells include the first P-type FETs including SiGe channels. The first P-type FETs have the deeper junction of the source/drain regions for Ion boost. Furthermore, the SRAM cells include the second P-type FETs (e.g., the pull-up transistor PU-1/PU-2) including Si channels. The second P-type FETs have the shallower junction of the source/drain regions for write margin improvement. For example, the lower alpha ratio (Ion of PU-1/Ion of PG-1) is obtained to gain the cell write margin and without impact the speed or induced extra cost. High channel strain P-type FinFETs (e.g., Ion/Ioff>10% gain) for the standard cells (e.g., the speed driven logic circuit) and high threshold voltage (Vt) P-type FinFETs (that includes purely Si channel without extra channel strain layer) of SRAM cells are provided for write margin improvement as well as low standby requirements. Extra high threshold voltage FinFETs are provided for the SRAM cells and the lower leakage requirement device.

In some embodiments, an integrated circuit (IC) is provided. The IC includes a plurality of a plurality of P-type fin field-effect transistors (FinFETs). The P-type FinFETs includes at least one first P-type FinFET and at least one second P-type FinFET. Source/drain regions of the first P-type FinFET have a first depth, and source/drain regions of the second P-type FinFET have a second depth that is different from the first depth. A first semiconductor fin of the first P-type FinFET includes a first portion and a second portion that are formed by different materials, and the second portion of the first semiconductor fin has a third depth that is greater than the first depth.

In some embodiments, an integrated circuit (IC) is provided. The IC includes a logic array including a plurality of logic cells arranged in rows and columns, and a memory array including a plurality of memory cells arranged in rows and columns. Each of the logic cells includes at least one first P-type fin field-effect transistor (FinFET). Each of the memory cells includes at least one second P-type FinFET. A first semiconductor fin of the first P-type FinFET and a second semiconductor fin of the second P-type FinFET include different materials. Source/drain regions of the second P-type FinFET and source/drain regions of the first P-type FinFET have different depths.

In some embodiments, an integrated circuit (IC) is provided. The IC includes a plurality of first cells and a plurality of second cells. Each of the first cells includes a plurality of first P-type fin field-effect transistors (FinFETs). Each of the second cells includes a plurality of second P-type FinFETs. The first P-type FinFETs of each of the first cells share a discontinuous semiconductor fin, and the second P-type FinFETs of the second cells positioned in a first line share a continuous semiconductor fin. Source/drain regions of the second P-type FinFETs and source/drain regions of the first P-type FinFETs have different depths.

The foregoing outlines nodes of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. An integrated circuit (IC), comprising: a plurality of P-type fin field-effect transistors (FinFETs), comprising: at least one first P-type FinFET over a semiconductor substrate; and at least one second P-type FinFET over the semiconductor substrate, wherein source/drain regions of the first P-type FinFET have a first depth, and source/drain regions of the second P-type FinFET have a second depth that is different from the first depth, wherein a first semiconductor fin of the first P-type FinFET comprises a first portion over the semiconductor substrate and a second portion over the first portion, wherein the first and second portions are formed by different materials, and the second portion of the first semiconductor fin has a third depth that is greater than the first depth.
 2. The IC as claimed in claim 1, wherein a second semiconductor fin of the second P-type FinFET and the first portion of the first semiconductor fin are formed by the same material.
 3. The IC as claimed in claim 1, wherein difference in depth between the first depth and the second depth is greater than 3 nm or 5%.
 4. The IC as claimed in claim 1, wherein difference in depth between the first depth and the second depth is from 3 nm to 15 nm or from 5% to 30%.
 5. The IC as claimed in claim 1, further comprising: at least one standard cell comprising the first P-type FinFET; and at least one SRAM cell comprising the second P-type FinFET.
 6. The IC as claimed in claim 1, wherein the source/drain regions of the first P-type FinFET and the source/drain regions of the second P-type FinFET comprise boron-doped SiGe.
 7. The IC as claimed in claim 6, wherein Ge atomic concentration in a channel region of the first P-type FinFET is from 5% to 45% and is less than Ge atomic concentration in the source/drain regions of the first P-type FinFET.
 8. The IC as claimed in claim 1, further comprising: a plurality of N-type FinFETs, wherein each of the N-type FinFETs comprises a Si channel region, and source/drain regions of the N-type FinFET comprise SiP, SiC, SiPC, SiAs, Si, or a combination thereof.
 9. An integrated circuit (IC), comprising: a logic array comprising a plurality of logic cells arranged in rows and columns, wherein each of the logic cells comprises at least one first P-type fin field-effect transistor (FinFET); and a memory array comprising a plurality of memory cells arranged in rows and columns, wherein each of the memory cells comprises at least one second P-type FinFET, wherein a first semiconductor fin of the first P-type FinFET comprises a first portion and a second portion over the first portion, and the second portion of the first semiconductor fin and a second semiconductor fin of the second P-type FinFET comprise different materials, wherein the second portion of the first semiconductor fin, source/drain regions of the second P-type FinFET and source/drain regions of the first P-type FinFET have different depths.
 10. The IC as claimed in claim 9, wherein the first P-type FinFETs of the logic cells positioned in the same column of the logic array share the first semiconductor fin, and the first P-type FinFETs of two adjacent logic cells positioned in the same column of the logic array are separated by an isolation P-type FinFET with an underlying active region formed by the first semiconductor fin.
 11. The IC as claimed in claim 9, wherein the first P-type FinFETs of each of the logic cells share the first semiconductor fin, and the first semiconductor fins of two adjacent logic cells positioned in the same column of the logic array are separated by a dielectric-base gate.
 12. The IC as claimed in claim 9, wherein the second P-type FinFETs of the memory cells positioned in the same column of the memory array share the second semiconductor fin, and each of the memory cells comprises an isolation P-type FinFET with an underlying active region formed by the second semiconductor fin.
 13. The IC as claimed in claim 9, wherein the second P-type FinFETs of two adjacent memory cells positioned in the same column of the memory array share the second semiconductor fin, and the second semiconductor fins of the logic cells positioned in the same column of the logic array are separated by a shallow trench isolation.
 14. The IC as claimed in claim 9, wherein the logic cells are selected from a group consisting of inverter, NAND, NOR, AND, OR, Flip-Flop, SCAN, or a combination thereof.
 15. The IC as claimed in claim 9, wherein the logic array and the memory array each further comprises: a plurality of N-type FinFETs, wherein each of the N-type FinFETs comprises a Si channel region, and source/drain regions of the N-type FinFET comprise SiP, SiC, SiPC, SiAs, Si, or a combination thereof.
 16. An integrated circuit (IC), comprising: a plurality of first cells, wherein each of the first cells comprises a plurality of first P-type fin field-effect transistors (FinFETs); and a plurality of second cells, wherein each of the second cells comprises a plurality of second P-type FinFETs, wherein the first P-type FinFETs of each of the first cells share a discontinuous semiconductor fin comprising a first portion and a second portion over the first portion, and the second P-type FinFETs of the second cells positioned in a first line share a continuous semiconductor fin, wherein the first and second portions are formed by different materials, and wherein the second portion of the discontinuous semiconductor fin, source/drain regions of the second P-type FinFETs and source/drain regions of the first P-type FinFETs have different depths.
 17. The IC as claimed in claim 16, wherein the discontinuous semiconductor fins of two adjacent first cells positioned in a second line array are separated by a dielectric-base gate.
 18. The IC as claimed in claim 16, wherein Ge atomic concentration in the discontinuous semiconductor fin of the first P-type FinFET is from 5% to 45% and is less than Ge atomic concentration in the source/drain regions of the first P-type FinFET.
 19. The IC as claimed in claim 16, wherein the first cells and the second cells each further comprises: a plurality of N-type FinFETs, wherein each of the N-type FinFETs comprises a Si channel region, wherein the discontinuous semiconductor fin comprises SiGe, and the continuous semiconductor fin comprises Si.
 20. The IC as claimed in claim 16, wherein the first cells are selected from a group consisting of inverter, NAND, NOR, AND, OR, Flip-Flop, SCAN, or a combination thereof, and the second cells are memory cells. 